The purpose of this invention is to solve the problem of the high costs, extreme hazard to safety and time consumption that is incurred with the initial placement of, or resetting of, power line conductors to their supporting structures, such as a transmission tower, that span areas, which prevent the construction process from using ground equipment. A power line conductor is typically a metal wire-shaped material that allows the flow of an electrical current in one or more directions. A transmission tower is typically a very tall usually a steel lattice tower which purpose serves to support an overhead power line conductor.
Currently, this is accomplished by utilizing helicopters when a span is to be constructed over inhospitable or unmanageable terrain. Reference is made to U.S. Pat. No. 4,421,301 for such a disclosure. The methods used have traditionally been hazardous to the ground crews as well as the pilot. Linemen would have to scale the transmission tower structures or poles to help receive the “sock line.” The sock line is a preliminary stringing line typically unrolled from a large spool supported on the ground at one end of a series of transmission towers. A typical sock line may be stranded cables of strong lightweight materials, such as steel, nylon or polyethylene. The sock line is strung through cable-stringing blocks or receivers attached to transmission towers along the entire length of the series of the transmission towers. Installation of transmission and distribution power conductor cables typically requires a stringing block having a sheave wheel. Stringing blocks typically include a rotatable wheel having a diameter ranging from about 10 inches to about 50 inches, with 16 to 22 inch wheels being most common. Current commercially available cable-stringing blocks use aluminum wheels in an aluminum frame. Reference is made to U.S. Pat. No. 8,398,057 to Tukachinsky and U.S. Pat. No. 6,375,163 to Carlson et al., which are incorporated herein by reference for describes of cable-stringing blocks.
The sock line has an end coupling for connection to an end of a power line. The benefit of the sock line is that it is considerably lighter and easier to manipulate than a power line cable. For that reason, sock lines are used in the initial stringing process. After the sock line is in place, an end of the power line cable is connected to an end of the sock line. The sock line is then pulled through the cable-stringing blocks thereby drawing the power cable line through the cable-stringing block to “string” the power cable line to the transmission towers.
In many instances, the helicopter would pull the sock line suspended from a vertical “long line,” sometimes as long as 250 feet. This line is weighted to ensure that the lightweight sock line does not sway too much in the wind. The helicopter pilot would then maneuver the aircraft to place the attached sock line into a receiving carriage attached to the structure and commonly assisted by a lineman on the structure or adjacent lift truck who is subjected to the possibility of falling at great distances and or being struck by the swaying of the attached weight of up to 200 lbs or more. The payout of the sock line is controlled by a brakeman who handles a reel drum from the starting point. If there is inadequate communication or teamwork between the pilot and brakeman, the reel will become too taught, causing flight malfunction, or too slack, causing a backlash in the reel, that has the result of snatching the aircraft out of the sky quickly. All of these incidents have happened in the past resulting in injuries and deaths.
While the current method is more time efficient than performing the operation by ground, it translates into many person-hours combined. The costs incurred can be very large due to the hourly rate of the helicopter operation as well as the cost of person-hours and equipment.